15 September 2016

Julia, Ian, and TD12 are scattered across the Atlantic

Today's update will be brief, as very little has changed since yesterday.

Surface wind field showing the circulations of the three active tropical cyclones in the Atlantic. (earth.nullschool.net)
Julia did eventually drift offshore after I wrote yesterday's post, and it also weakened to a tropical depression. It is expected to dissipate this weekend, but should remain virtually stationary the entire time due to a lack of steering flow.  This morning it is centered 85 miles east of the SC/GA border, with the "business end" (heavy rain, and thunderstorms, and strongest winds) displaced to the east of the center and away from land.

Sunrise over Tropical Depression Julia on Thursday morning.
Ian is still a moderate tropical storm with 50 mph peak winds, but remains embedded in a high-shear environment. The center is about 750 miles south-southeast of Newfoundland, but as you can see in the satellite image below, a frontal boundary is forming to its south, a tell-tale sign that it is transitioning to an extratropical cyclone.  NHC will likely cease writing advisories on it today or tomorrow.

And finally, Tropical Depression 12 is still forecast to battle with dry air for the next few days, but probably have a shot at intensification next week.  Should it reach tropical storm status, the next name on the list is Karl. It's presently not looking very ominous... just a low-level swirl with some widely scattered thunderstorm activity to its south.

The long-range forecasts are worth paying some attention to, at least to start watching for trends and consistency.  The plot below shows track forecasts from a variety of dynamical models out to 5-7 days, as well as the NHC forecast (black line).  There is general agreement that it will continue its westward motion and reach the area north of the Leeward Islands by late next week.  It is far too early to say anything certain about the intensity at that time, but for what it's worth, today's model runs indicate it would not be a hurricane at that point.

Stay tuned!

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